1. Field of the Invention
The present invention relates to a LED driving device, and in particular to a multi-channel LED driving device.
2. Description of Prior Art
Light emitting diodes (LEDs) have high luminous efficiency, long service time, widely operation temperature and environmental mercury-free, making them beyond the incandescent and fluorescent light bulbs, and led lighting field into a new solid-state lighting era.
However, the service time and light illuminating intensity of the LED is affected by its forward-bias and current to temperature characteristics, therefore, using a constant current is an optimal method to drive LED used in the lighting field and that can improve the power efficiency. Also, a multi-channel LED circuit including a plurality of LED strings composed of multiple LEDs electrically connected in parallel must drive the LED strings at the same time. However, due to different internal resistances of the LEDs, the conducting currents provided by a voltage source flowing through the LED strings must be different, and this will result in different illuminating brightness of the LED strings, the efficiency of the multi-channel LED circuit is accordingly reduced.
Therefore, it is desirable to achieve the objective of current-sharing control of the multi-channel LED driving circuit.